Brush and method of making same



July 3l 195] L. R. B. HERVEY l 2,562,716

BRUSHES AND METHOD OF' MAKING SAME Filed Aug. 9, 1945 Patented July 31,1951 BRUSH AND METHOD F MAKING SAME Laurence R. B. Hervey, Concord,Mass., assignor, by mesne assignments, to Rubberset Company, Newark, N.J., va, corporation of New Jersey Application'August 9, 1945, Serial No.609,812

Claims.

This invention relates to the manufacture of brushes. More particularly,it relates to a new and improved method for securing the bristle tuftsto the brush handle. It relates also to the resulting product.

My invention is especially directed to the manufacture of brushes ofthat type wherein the bristles are formed of nylon or otherthermoplastic or fusible synthetic material. It is especially concernedwith an improved method by which the tufts of bristles are firmly bondedtogether and are secured at their b'utt or root ends to the handle orsimilar supporting member in such manner that loosening or detachment ofthe individual bristles or bristle layers is prevented.

My method is particularlysuitable for use in securing together and to abrush handle tufts formed of a synthetic thermoplastic material such asnylon in lamentary form. This is accomplished in a way to secure adegree of adhesion never previously obtainable with synthetic bristles.The firm bond, which reduces the danger of the bristles becomingloosened and falling out, thereby greatly increasing the life of thebrush, is largely secured even without utilizing the usual metallicferrule surrounding the lower end of the handle and bristle knot.Generally, however, it is preferred to retain the conventional ferrule.

The proper bonding and setting of bristles of nylon and similarsynthetic thermoplastic bristle materials during the manufacture ofbrushes has heretofore been a very difficult manufacturing y operation.This is especially the case in making brushes of the paint brush typewherein the bristle knot is secured to a handle or supportin member ofwood or other material.

Usually in this type of brush a ferrule is employed to unite the bristlebody with the handle, the ferrule being arranged to surround portions ofeach and being secured by nails, or the like, to both. Because of thefusible character of the synthetic thermoplastic bristles attempts havebeen made to rely upon their fusing for bonding purposes. However,satisfactory adhesion of the bristles in this manner and their unionwith a handle or other supporting member by means of a ferrule/ has notgenerally been secured. As a result the bristles have loosened andfallen out of the brush, and the life of brushes utilizing syntheticbristles has consequently been unduly shortened.

In settin bristles of nylon or other thermoplastic syhrghetic materialit has been suggested to fuse t butt ends of the bristles together bymeans of heat while the bristle tufts are secured at their butt ends inthe usual metal band or ferrule. In utilizing this type of bond reliancehas .been placed on the bristle knot becoming fused to not only hold thebristle together but also to cause them to adhere to the metal ferrule.Nails or screws have sometimes been passed through the ferrule into thebristle knot to assist in maintaining the assembly.

'Ihe foregoing method of securing the bristle body to the handle is,however, objectionable for a number of reasons. The high temperaturesrequired maintained over a sufficient period lto effect the desiredfusion, tend to cause some disintegration of the nylon or othersynthetic thermoplastic material, with consequent weakening of the bondbetween the individual bristles. Unless nails are driven through theferrule into the bristle knot the adherence of the fused thermoplasticmaterial to the metal of the ferrule is not suicient to provide a verysatisfactory bond. And if nails are driven into the bristle knot throughthe ferrule the depth of fused plastic is generally insufficient topermit such nailing without breaking the knot and causing separation ofthe individual bristles at a point opposite that where the nailspenetrate the brush. The methods for setting bristles of syntheticthermoplastic material in brushes that are now available have generally'not been very satisfactory. and the resulting brushes have beencharacterized by weak bonding between the individual bristles andbetween the bristle body and the brush handle or other bristlesupporting member.

It is'the primary object of this invention to provide an improved methodand means for securing bristles of a synthetic material such as nylon,or other thermoplastic synthetic bristle material, together and to thebrush handle or other supporting member used to retain the bristles.

Another object of my invention involvesv the securing of the desiredimproved adhesion between the bristle tufts and brush handle by aprocedure and means through which damage or disintegration of thesynthetic bristles is avoided. The bristles are bonded to the handlewithout the necessity for driving nails or screws into the fused bristleknot, thus avoiding separation of individual fibers usually resultingfrom the use of suchattachment elements. f

It is another object of this invention to provide a 'method and meansfor attaching synthetic thermoplastic bristles to a brush handle orother supporting member which is simple and effective,

and which can be readily practiced or applied inescano 3 in existingbrush manufacturing establishments without the necessity for providingadditional equipment. A

A further object of this invention is to provide a method and means forthe attachment of bristles of the character described to brush handleswhich will-result in a bond that is permanent and secure, regardless ofwhether or not the brush includes the usual metal ferrule now customaryin brushes. These and still further objects of my invention will beapparent from the ensuing disclosure of certain illustrative, preferredembodiments thereof. K

My improved method and means for setting synthetic thermoplasticbristles in the bristle knot, and for securing that bristle knot to thebrush handle in a tight bond. may best be described with reference tothe annexed drawing wherein: i

Fig. 1 is a view partly in side elevation and partly in section, whichillustrates the method of assembling the various parts of a brush inaccordance with my method. The view shows the variom elements comprisingthe brush separated somewhat, so that the method of bonding the bristleknot to the brush handle will be more readily apparent;

Fig. 2 is a cross-sectional view taken on the line I-I of Fig. l andlooking in the direction of the arrows:

Fig. 3 is a side elevational view, some parts being broken away forclearness of illustration, of a completed brush incorporating myimproved bond; and

Pig. 4 is a cross-sectional view taken on the line l-l of Fig. 3,looking in the direction of the arrows.

While my invention may be conveniently described with reference to themanufacture of a paint brush, it is obvious that it is not restricted tothe manufacture of such brushes but is of general application whereverthe problem is encountered of securingbristles of a syntheticthermoplastic material such as nylon to a handle or supporting member.

Referring more particularly to the drawing, the brush includes the usualhandle 5, which may be of wood or any other suitable material, and whichmay be formed with the enlarged lower portion t to which the bristlesare to be attached. The securement member 1, which may be a metal plate,is first secured to the lower portion s of handle 5, by nails or screwsl, or in some other suitable manner. As shown, the plate 1 may be set ina slight distance from each edge of the lower end section of lowerportion 6. The metal plate 'I may be channel-shaped in cross-section,and may be provided with a series of perforations i in each dependingleg of the channel. The screws or nails l, securing the metal plate tothe lower end t of the handle l, may rest against the inner iiat surfaceof the top or back of the channeled metal plate member. While a metalplate 1 of channel cross-section is illustrated in the drawing and forsome purposes will be found superior 'for securing the bristles to thehandle 5, the metal plate may be constructed to have crosssections ofvarious other forms. It may, if desired. be formed as a complete cup.

The bristles Il, formed of nylon or some other synthetic thermoplasticmaterial suitable for -use in forming brush bristles, after beingassembled in any suitable marmer to form the desired bris` tle bunch,may be fused together at the butt ends of the bristles to provide thebristle knot I2. If

4 desired, this may be done while the tuft or tufts of bristles are heldtogether in the ferrule Il, which may be of metal, so as to secure thebenefit of any adhesion between the bristle knot and the metallicferrule resulting from the fusion. 1n fusing the bristles at their rootor butt ends to form the bristle knot I2, heat is applied to the bristleends in any suitable manner and at a high enough temperature to fuse theends of the bris- .tles and cause them to adhere together in the form ofa solid bristle knot. In order to accomplish this it may be necessary toheat the butt ends of the tuft or tufts of bristles to a temperatureabove the melting point of the thermoplastic bristle material which, inthe case of nylon, is

' about 450 F. (230 C.) For many purposes, however. heating to thefusion temperature is not necessary, as asynthetic thermoplasticmaterial may soften under the influence of heat at a temperature belowits melting point to a suillcient extent to permit the root ends of thebristles to adhere together to form the desired bristle knot.

As shown most clearlyin Pig. 4, in the manufacture of paint brushes,particularly the larger sizes, it is frequently desirable to provide adividing member or plug I5, which may be a block of wood or othersuitable material, this being arranged in the bristle knot to provide acentrally-disposed space serving to render the bunch more pliable duringforward and backward strokes of the brush while painting or brushing. Insome instances, particularly in smaller brushes. the plug may beomitted, and my invention may be practiced either with or without thiselement. If used, the plug should be properly positioned before heatingthe butt ends of the bristle tufts to secure the bristle knot I2,although it may, if desired, be pressed into the bristle knot after theroot ends of the bristles have been heated and are in a soft or plasticcondition. Several of such plugs may be utilized if desired.

The metal plate 1 may be heated, as by means of a torch, by inductionheating, or by any other suitable means. The metal plate is preferablyheated to a temperature of between 300 C. and 400 C., although somevariation from this range may be desirable depending on the nature ofthe thermoplastic bristle material used. The handle i is quicklyinserted into the ferrule I3 containing the bristle knot I2 after theheated metal of the plate 1 has caused softening or melting of thesynthetic thermoplastic material to an extent suiiicient to permit themetal plate to be embedded in the fused area of the bristle knot I2. Asa practical matter it is usually desirable to embed the heated metalplate 1 in the bristle knot I2 while the latter is held in the ferruleI3 and in a plastic or fused condition. The embedding of the heatedmetal plate 1 in the bristle knot I2 may advantageously take place as astep immediately following that of forming the bristle knot I2 in theferrule II by the application of heat.

The assembly is now permitted to cool and the bristles II are tightlysecured to the handle C by means of the metal plate 1 which is fastenedto the handle and is embedded in the bristle knot I2. The bond betweenthe handle t and the bristles II thus produced is far superior to thatobtainable by other previously available methods for securing bristlesof synthetic thermoplastic material to brush handles or other supportingmembers. This bond is secured without causing disintegration of thenylon or other synthetic thermoplastic bristle material. Moreover, whenthe bristle knot is so formed the danger of shed-l ding or loosening ofindividual bristles, such as in the outer layers of the bristles, isreduced to a minimum.

After the metal plate 1 is embedded in the bristle knot I2, the ferruleI3 may, if desired, be removed as it does not play an important role inbonding the bristles II to the handle 5. For many purposes, however, itis desirable to retain the ferrule as a part of the permanent assembly,thus from the appearance standpoint it is a desirable element in acommercial brush structure of this type. When so used it may be nailed,held by screws, or otherwise securedto the brush handle 5 and, in thatevent does strengthen the entire assembly somewhat by firmly embracingand holding together the handle 6 and bristle body II. It assists tosome extent also in preventing loosening and detachment of the outerlayers of the bristles which are generally less firmly bonded to thebristle body. However, as indicated, my invention may be practicedwithout retaining the ferrule in the nal assembly, should this beconsidered desirable in any particular instances.

Various modications of or variations in the preferred and illustrativeembodiments of the invention, which have been described, may be adopted.Thus the metal plate 1 might be first embedded in the bristle knot I2,and then secured, by nails or screws, or any suitable, special means, tothe brush handle 5. Also, the extent to which the metal plate isembedded in the bristle knot may be varied, depending on the degree ofbond desired and the nature of the synthetic thermoplastic bristlematerial. While it is ordinarily not desirable, nailing or the insertionof screws through the ferrule into the bristle knot may also be utilizedas an additional securement means. While my invention is particularlyadapted `for paint brush construction, my method is of value in themanufacture of brushes of other types.

It is intended that the foregoing modifications, as well as otherchanges in my process and brush construction as described, shall beconsidered as falling within the scope of my invention, to the extentthat they are comprehended within the appended claims.

I claim:

1. A brush comprising a bristle body of synthetic thermoplasticbristles, one Y end of said bristle body being fused and resolidied toform an integral knot of the therm lastic material of which saidbristles are forme a handle having one end adjacentsaid knot, and ametallic member having a portion secured directly to said end of thehandle and a portion embedded in the outer end of said knot for securingsaid bristle body and handle together, said second mentioned portionhaving recesses extending transversely of the axis of the bristle bodyand arranged to interlock with the material of said knot.

2. The method of manufacturing brushes having bristles formed of asynthetic thermoplastic material which comprises assembling a bunch ofbristles with their butt ends encircled and held firmly together,applying heat to the butt ends of the bristles while so held to fuse thesame into an integral fused bristle knot, heating a metallic securementmember to a temperature substantially above the melting point of thethermoplastic material, embedding a portion of said heated securementmember directly in the outer end of said bristle knot, and in the courseof forming the brush providing a direct' and firm a handle, whereby saidbristle body is secured to said handle in a firm bond independently ofan encircling ferrule.

3. The method of manufacturing brushes having bristles formed ofsynthetic thermoplastic material which comprises assembling abunch ofbristles with their butt ends encircled *and held firmly together,applying heat to the butt ends of the bristles while so held to fuse thesame into an integral fused bristle knot, providing a metallicsecurement member with surfaces extending transversely to its axis,heating said member to a temperature substantially above the meltingpoint of the thermoplastic material, embedding a portion of said heatedsecurement member provided with said surfaces directly in the outer endof said bristle knot by forcing the member in an axial direction intosaid knot, and in the course of forming the brush providing a direct andfirm connection between said securement member and a handle whereby saidbristle body is secured to said handle in a firm bond independently ofan encircling ferrule.

4. The method of manufacturing brushes having bristles formed of asynthetic thermoplastic material which comprises assembling a bunch ofbristles with their butt ends encircled and held firmly together,applying heat to the butt ends of the bristles while so held to fuse thesame into an integral fused bristle knot, providing a metallicsecurement member with surfaces extending transversely to its axis,heating said member to a temperature substantially above the meltingpoint of the thermoplastic material, embedding a portion of said heatedsecurement member provided with said surfaces directly in the outer endof said bristle knot by forcing the member in an axial direction intosaid knot while the latter is still hot and soft, and in the course offorming the brush providing a direct and firm connection between saidsecurement member and a handle, whereby said bristle body is secured tosaid handle in a firm bond independently of an encircling ferrule.

5. A brush comprising a bristle body of synthetic thermoplasticbristles, one end of said bristle body being fused and resolidified toform an integral knot of the thermoplastic material of which saidbristles are formed, a handle having one end adjacent said knot, and ametallic member having a portion secured directly to said end of thehandle and a portion embedded in the outer end of said knot for securingsaid bristle body and handle together, said second menf tioned portionhaving walls parallel to the general direction of the bristle body, andsaid walls having interlocking means extending in a direction transverseto the general direction in which said bristle body extends and arrangedto interlock with the material of said knot to prevent endwiseseparation of the handle and knot.

LAURENCE R. B. HERVEY.

REFERENCES CITED The following references are of record in 'the file ofthis patent:

UNITED sTATEs PATENTS Number Name Date 1,695,124 Reese Dec. 11. 19282,303,800 Swann Dec. 1, 1942 2,316,870 Jacob, Jr. et al. Apr. 20, 19432,341,823 Smith Feb. 15,1944

